What size is your heatlamp bulb? They go as high as 250Ws (just make sure the housing is rated for it). They also have 150s, 100s, 75s... I'm guessing you have a smaller wattage. If you have ANY wire openings around the side of your brooder, then wrap cardboard pieces around the sides. Or, as someone else suggested, use two heat lamps. Do make sure that the thermometer is directly under the lamp. That's where you want it to be @95, and the rest a bit cooler so that they have places to go if it IS to warm for them. It does depend on how old they are too...if they're just a few days old, you will want it close to 95. But if they're a week or two old, probably 85 or so would be okay. Their behavior will let you know. If they tend to huddle quite a bit under the lamp's rays, it's not warm enough. But if they spread out for resting, then it's fine.